title: Regulation of intracellular Ca(2+)  by reactive oxygen species in osteoblasts treated with antimycin A.
abstract: This study evaluated the effects of antimycin A (AMA), an inhibitor of electron transport in mitochondria, on the release of intracellular calcium ion ([Ca(2+) ](i) ), ROS and bone resorbing factors in osteoblastic MC3T3-E1 cells. Pretreatment of osteoblasts with trolox, a ROS scavenger, and cyclosporin A, a potent inhibitor of calcium release from mitochondria, prevented the AMA-induced increases in [Ca(2+) ](i) . However, [Ca(2+) ](i) increase by AMA was unaffected by dantrolene, which blocks the ryanodine receptor channel of the endoplasmic reticulum. BAPTA/AM (an intracellular Ca(2+) chelator), dantrolene and cyclosporine A did not reverse the effect of AMA on ROS release. We also investigated whether intracellular calcium release inhibitor and antioxidant protect against AMA-induced bone resorbing cytokine release. Trolox prevented the release of receptor activator of nuclear factor-κB ligand (RANKL), IL-6, and TNF-α induced by AMA. Moreover, the increased IL-6 and TNF-α release by AMA was markedly reduced by BAPTA/AM and cyclosporin A. However, BAPTA/AM did not reverse the effect of AMA on osteoprotegerin and RANKL. Taken together, these results demonstrate that mitochondrial ROS generation and Ca(2+) influx by AMA is required for osteoblast death and bone resorbing cytokine release.
authors.affiliation: Department of Food and Nutrition, Kyung Hee University, 1, Hoegi-dong, Dongdaemun-gu, Seoul, 130-701, Korea. cheunmi@hanmail.net
authors.forename: Eun Mi
authors.initials: EM
authors.lastname: Choi
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000968:Antimycin A / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D016923:Cell Death; D016207:Cytokines / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism* / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D016207:Cytokines; D015850:Interleukin-6; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; C025940:bone resorption factor; D000968:Antimycin A; D002118:Calcium